The overall shape of a golf club head is often dictated by a number of functional considerations, each of which has a bearing on a golf club's performance. One of the most important of such considerations is related to the distribution of a club head's weight in relation to the longitudinal axis of a club shaft.
During the motion of swinging a golf club, the club shaft acts as the radial arm between the center of the swing and the arc defined by the club head. Proper weight distribution of the club head at the end of the shaft is of critical importance during this swinging motion, as it is desirable to achieve a balance which gives the club an "even" feel throughout the swing.
But other less well-recognized considerations also impact golf club performance. For example, the shape of the club head is important during the swing with respect to air flow. A club of radically asymmetrical dimensions or large surfaces may create dissimilarities in air flow, adversely affecting the feel of the club through the swing. And a further functional consideration in club head design is club contact with the ground during the "bottom" portion of the swing.
That portion of the sole of the club head which actually contacts the ground at the "bottom" of the swing is typically referred to as the bounce surface, while the plane of contact defined between the sole and the ground at this point is called the bounce plane. One purpose of the bounce surface is to prevent the rotational force of the swing from driving the club head into the ground as the club head travels through this bounce plane (a phenomenon also referred to as "submarining"). Unfortunately, contact between the bounce surface and the ground has the negative side effect of inducing drag, which slows the momentum of the club head just prior to contact with a golf ball.
Prior art club heads have failed to comprehensively address these considerations. With respect to drag, for example, Stone, U.S. Pat. No. 2,447,967, discloses a golf club having a sole the bounce surface of which comprises a large surface area. And Morton, U.S. Pat. No. 1,835,718, teaches a golf club whose body includes a forwardly curved wing which purposefully induces drag throughout the swing, decreasing a club's momentum.